TPU filament is a flexible 3D printing material suitable for phone cases, gaskets, and shock-absorbing parts. This article covers everything you need to know, from choosing Shore Hardness and printer settings to troubleshooting common issues.

If you've ever wanted to print soft, shock-absorbing phone cases, rubber gaskets, or parts that need to bend without breaking — TPU Filament is the answer you're looking for. This material is rubber-like, flexible, impact-resistant, and can return to its original shape after being compressed, unlike PLA or PETG which are much harder and more brittle.

In 2026, TPU has gained significant popularity among general 3D printer users because newer printers like Bambu Lab and Prusa MK4S support TPU printing much better than in the past. This article will guide you through everything about TPU, from choosing hardness and printer settings to troubleshooting common issues.

What is TPU and How Does It Differ from General Filaments?

TPU (Thermoplastic Polyurethane) is a flexible filament material that can be printed with FDM printers. It has a block copolymer molecular structure consisting of alternating hard and soft segments, allowing parts to be flexible while maintaining their shape well.

Compared to PLA or PETG, which are rigid materials, TPU has distinct differences:

• High flexibility — can stretch 300-700% before breaking, while PLA breaks at 3-6%.
• Impact resistance — absorbs impact energy through temporary deformation.
• Wear resistance — commercially used for shoe soles and tires.
• Oil and grease resistance — suitable for industrial and automotive applications.
• Remains flexible in cold weather — maintains flexibility down to -40°C.

What is Shore Hardness? How to Choose Hardness

TPU has a hardness level called Shore Hardness, measured in A units. The lower the number, the softer and more flexible the material. Common levels found in the market include:

• Shore 85A — Very soft, feels like silicone rubber. Suitable for applications requiring high flexibility, such as vibration dampening pads or soft-edged phone cases, but harder to print.
• Shore 95A — The most popular standard hardness. Balances flexibility and ease of printing. Ideal for beginners.
• Shore 98A — Semi-rigid and semi-flexible. Easiest to print among TPU types. Still offers some flexibility but is harder. Suitable for snap-fit parts.

Recommendation for beginners: Always start with Shore 95A. It's the best starting point. Once you're proficient, then try softer or other special TPU types.

Printer Settings for TPU

TPU requires very different settings from PLA because its flexibility can easily cause the filament to buckle in the extruder system. Here are the key settings you should know:

Nozzle Temperature: 220-240°C for 95A generally. Start at 225°C and adjust according to the brand you use.

Bed Temperature: 40-60°C. TPU doesn't need high heat like ABS because it rarely has warping issues. Too high a bed temperature can cause the part to stick too firmly, making it difficult to remove.

Print Speed: 20-40 mm/s for standard TPU, much slower than PLA. High speeds cause filament to build up in the nozzle and lead to clogging. If using new High-Flow TPU from Bambu or Polymaker, you might be able to print up to 60-80 mm/s.

Retraction: Set low or turn off. For Direct Drive, use 0.5-2 mm at 25-40 mm/s. Excessive retraction can cause flexible TPU filament to coil up in the extruder and clog.

Cooling Fan: 30-60%. Not as much as PLA, because if it cools too quickly, layers won't adhere well.

Bowden vs. Direct Drive — The Most Important Factor for TPU

This is the most crucial factor for printing TPU: your printer's extruder system will determine if you can print successfully.

Direct Drive Extruder (motor located directly on the print head) is the best option for TPU. The filament travels a short distance directly from the gear into the hotend, reducing the chance of buckling. Printers that support this well include all Bambu Lab models, Prusa MK4S, Voron, and machines with a Direct Drive Upgrade already installed.

Bowden Extruder (motor separate from the print head, with a long PTFE tube), such as the original Ender 3, can print 95A TPU but requires significantly reduced speeds (15-25 mm/s) and all retraction turned off. Expect more stringing than usual. For TPU softer than 90A, it's recommended to upgrade to Direct Drive first.

Filament Drying Before Use — Very Important!

TPU absorbs moisture from the air very easily (hygroscopic), even if stored for a short time. If the filament has absorbed moisture, these problems will occur:

• Bubbles and popping sounds at the nozzle.
• Rough and porous surface finish on parts.
• Poor layer adhesion, weak parts.
• Excessive stringing.

Solution: Dry TPU at 65-70°C for 4-8 hours before printing. Do not exceed 75°C, as TPU may soften and the filament on the spool may tangle. After drying, store in an airtight container with Silica Gel to maintain dryness.

Best Uses for TPU

TPU opens up a world of possibilities that PLA or PETG cannot achieve:

• Phone and tablet cases — absorbs impact, non-slip, durable. Shore 95A is ideal.
• Gaskets and seals — making waterproof O-rings, leak-proof gaskets, gap fillers.
• Vibration dampeners and shock absorbers — machine vibration bases, table leg pads.
• Flexible hinges — living hinges that bend without breaking, clips and latches.
• RC car tires — RC car tires with flexibility and durability.
• Cosplay props — armor parts that curve with the body.
• Grips and handles — soft-touch, non-slip tool handles.

Common Problems and Solutions

Problem: Filament Clogging in Extruder
Cause: Excessive retraction, or using Bowden with too soft TPU.
Solution: Reduce retraction distance to 1-2 mm or turn off completely, increase nozzle temperature by 5-10°C, reduce print speed.

Problem: Excessive Stringing
Cause: Moisture in filament, too high temperature, incorrect retraction settings.
Solution: Dry filament, reduce temperature by 5°C, enable Coasting 0.2-0.5 mm.

Problem: Layers Not Adhering, Separating
Cause: Cooling fan too fast or temperature too low.
Solution: Reduce fan to 20-40%, increase nozzle temperature, reduce outer wall print speed.

Problem: Part Stuck to Bed, Cannot Remove
Cause: Bed temperature too high or too much adhesive used.
Solution: Reduce bed temperature by 5-10°C, use a textured PEI sheet — TPU will release itself when the bed cools down.

Conclusion: Why TPU is Worth Learning

TPU may seem difficult at first, but once you understand the principles, it's a filament that opens up entirely new possibilities that rigid materials cannot. With a Direct Drive Extruder, well-dried filament, and sufficiently slow speed settings, you can print TPU consistently and reliably.

For beginners, it's recommended to start with TPU 95A from reliable brands like eSUN or Polymaker, which are readily available and have consistent quality. Once you successfully print and gain proficiency, then try softer or other special TPU types as needed. The flexibility of TPU will surely change your perspective on what 3D printing can create.

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